Voice operated repeater



June 27, 1939- E. c. ERTNoLLI ET AL l 2,154,135

VOICE OPERATED REPEATER Filed May 22, 1937 2 Sheets-Sheet 1 4 5 f. l A

ATTORNEY June 27, 1939. E, c. SER1-Nou.; ET'AL 2,164,185

VOIC OPERATED REPEATER Filed May 22, 1937` 2 Sheets-Sheel 2 Patented .un l27, 1939 UNITED STATES voIcE OPERATED REPEATER Edward C. Bertnolli and Kenneth D. Cornell, Kansas City, Mo., assignors to Great Lakes Pipe Line Company, tion of Delaware Kansas City, Mo., a corpora- Application May 22, 1937, Serial No. 144,170

5 Claims.

Our invention relates to voice operated repeaters, and more particularly to a two-way transmission circuit containing oppositely directed repeaters which are conditioned for operation one at a time.

In the repeaters or ampliers now in general use, artificial balancing net works are employed which control the gain output of the amplifier. These networks are used to simulate the line to which the repeater is connected, and areplaced in the circuit with a hybrid coil. The gain of the repeater is limited to the balance of the hybrid coil and to the impedance matching of the networks to the actual line. Furthermore, the amplified energy is divided-one-half of it being absorbed by the articial line, and the other half of the tube output being used as line amplication energy.

Numerous concerns employ field telephones and utilize spur lines between amplifying stations. Under these conditions it is very diicult to get a good network balance and this penalizes amplication.

One object of our invention is to provide an electronic voice operated repeater, in which neither a hybrid coil nor balancing networks are used.

Another object of our invention is to provide a repeater system in which the received signal is amplified directly, enabling any desired gain to be obtained, resulting in better energy quality, as distortion by a mismatched network is eliminated,

A further object of our invention is to improve the operation of a voice operated repeating system, particularly as regards positive directional operation and freedom from internal high frequency circulatory currents or internal oscillation.

In general, our invention contemplates the provision of a two-way repeating system which under the normal or no-voice condition has both the west to east and east to west input sides of the system in operative condition, and the outputs of the West to east and east to west sides standing open or cut off from-the line, the repeater being in condition to amplify in either direction without the possibility of setting up an internal high frequency circulatory condition.

When voice or other energy is introduced in either direction, that side is placed in amplifying condition, while the opposite side is automatically blocked out, making it impossible for it to conflict with the operation of the amplifying side.

In the interests of clarity and simplification, our invention will be described with respect to voice operated circuits and two-way transmission, it being understood, however, that the invention is applicable to other types of transmission and to one-way as well as two-way transmission or amplification.

In the accompanying drawings, which form part of the instant specification, and which are to be read in conjunction therewith, and in which like reference numerals are used to indicate like parts in the various views;

Fig. 1 is a diagrammatic view of a Voice operated repeater system shown in the normal or no'- `voice condition, those parts of the circuit carrying current being shown in heavy lines.

' Fig. 2 is a diagrammatic view of the system shown in Fig. 1, amplifying signals in the west to east direction, those parts of the circuit carrying current being shown in heavy lines.

More particularly, referring now to the drawings, the line from the west is shown as comprsing conductors I and 2, supplying energy to the primary 3 of a transformer, the secondary 4 of which is center tapped to the cathode 5 of thermionic tube 6. `The ends of the secondary 4 are connected by conductors 'I and 8, respectively, to grids 9 and IIJ of the tube 6. The plates II and I2 of the tube 6 are connected by conductors I3 and I4 to the ends of the primary coil I5 of a transformer. The coil I5 is center tapped by conductor I 6 and connected to ground I'I. The secondary coil I8 is inductively coupled to the primary I5. The primary coil I9 of a transformer is connected across the secondary coil I3 by means of conductors 20 and 2 I. A secondary coil 22 is inductively coupled with the primary coil I9. Coil 22 is center tapped by conductor 23, which center tap is connected to one end of resistance 25 by conductor 24. The other end of resistance 25 is connected by conductor 26 to the cathode 2'I of full wave rectifier tube 28. The ends of secondary 22 are connected to plates 29 and 30, respectively, of the tube 28. The output of the secondary coil I8 is impressed upon the grid 3I of the thermionic tube 32 through conductor 33, the cathode 34 of the tube 32 being connected to the other side of the secondary I6 by conductor 35. The plate current supplied to tube 32 is from batteryl 36, the plate current flowing from the positive terminal of battery 36 through the primary coil 31 of a transformer, through conductor 38 to the plate 39, to cathode 34, through resistance 40, through conductor 4I, to the negative side of the plate battery 36. Variations in the plate current through primary 3'I will be inductively reproduced in the secondary coil 42, across which the conductors 43 and 44 of the line are connected.` Across the lines I and 2, by means of conductors 46 and 4l, is also connected the secondary coil of a transformer, the primary'coil, 48, of which is placed in the plate circuit of thermionic tube 58. The primary coil 49, of which coil 58 is the secondary, is connected across lines. 43 and 44 by means of conductors 5I and 52. Coil 49 is analogous to coil 3, while coil 5I]r is analogous to coil 4. The center of coil 58 is connected to the cathode of thermionic tube 56. The grids 59 and 68 of tube 56 are connected by conductors 51 and 58 to the ends of coil 58f.. The

plates 6I and 62 of thermionic tube 56 are connected by conductors 63 and 64 across the primary' coil 65 of a transformer, which isl center tapped by conductor 66 to groundA 61. The coil 65- is inductively coupled to its secondary coil68, it being understood that coils 65 andv68 are analogousto coils I5 and I8.

The primary coil 69 of a. transformer is )connected across coil 68 by means of conductors18 A secondary coil 12 is inductivelylcouand 1I. pled to the primary coil 69, and has its center tapped by conductor 13. Center tap 13 isv connected by conductorv 14 to one'sideA of resistance 15, the other side of which is connected by conductor 16 to the cathode 11 ofthe full wave rectiiier tube 18. Rectifier tube 18 is vprovided with anodes 1'9 and 88 connected across the terminals of secondary coi1`12. A portion of the output of secondary coil 68 is impressed'upo'n the grid v8| of tube 58, by means of conductor 83, the other side of coil 68 being connected by conductor to cathode 84 of the tube 50. The plate supply for the tubev 50 is from battery 86,current'flowlng from the positive terminal of battery86 through the primary coil 48 of the transformer, through 'conductor 88 to the anode 89 ofthe tube 58, thence, to cathode 84, through resistance 98, through conductor 9| to the other side of the battery 86. A thermionic tube-92 has its anode 93 connected by conductor 94 `to the positive terminal of a battery 95. The cathode 96 of the tube 92 is connected by conductor91 to ground 98. Resistance 99has one end thereof grounded at |88. The other end of resistance 99is connected by conductor I8I to ther negative terminal of battery 95. Another control tube |82 hasits anodel83 connected by conductor |84 to `:the positive terminal of a battery' |85. Thecathode |06 of tube |82 is connected by conductor I81.to the ground |88. -A resistance Y|89 is grounded at II8. The other side of resistance |09 is connected by conductor I I I to the negative terminal of battery |85.

In operation, referring now to Fig. 1, which shows the normal or no-voice condition of the. system, it will be observed that current is owing from the positive terminal of battery through conductor 94 to plate 93 to cathode 96, to ground 98, to ground |88, through resistance 99, through conductor I8I, to the other side of the plate battery 95. The IR drop of the plate current through resistance 99 creates a voltage across the resistance, that end of the resistance 99 which is connected to cathode being positive `and the other end of the resistance being negative. It will be observed that the negative end of resistance 99 is connected by resistance II2 to the grid 3| of tube 32. Since the cathode 34 of tube 32 is grounded through resistance 48 at ground II3, grid 3| will be highly negative with A tential upon anodes 6| and 62 of tube 56 through conductorsf63 and 64. The cathode 55 of tube 56 is connected to resistance II4, and conductor II5 to the negative side of resistance 99. It will be apparent from the foregoing that as long as plate current is ilowing through the 'circuit of tube 92, that tube 32 will be blocked and tube 56 willbe in operative or signal receiving position.

Similarly, current will be flowing from the posf: itive terminal of battery |85 through conductor |84, through anode |83, through cathode |86,

v through conductor |81, to ground |08, to ground .II8-,. through resistance |89, through conductor III, tothe other side of battery |85. The IR drop through resistance I 89 will cause a potential I4 to anodes I I and I2 of tube 6 to cathode 5 of tube 6, through resistance I I 6, through conductor II1,- to thev negative side of resistance |89.

Similarly, it will also be observed that the negative yside of resistance |89 is connected by resistance I I8 to the grid 8| of tube 58. ode-84 of tube 58 is connected by resistance 98 to ground I I9, which is thus connected to the ground II 8 and hence to the positive side of resistance |89. It will beclear that grid 8| of tube 58 will -be'highly negative with respect to the cathode of tube 58 4as long as current is flowing through the plate circuit of control tube |82, thus blocking or biasing out tube 58.

In the normal or no-voice condition therefore, as has been just described, the input tube 6 of vthe vwest to east amplifier, and the input tube 56 of the east to west amplier will be in operative lcondition with the output tube 32 of the West to east amplifier and the output tube 58 of the east to west amplifier in blocked or inoperative condition.

Let -us now consider the operation of the system. When a signal is received from the west side of vtheline, the energy in the line will pass through. coils 3, and 45. with an -output coil 48, which, furthermore, is blocked, nothing will occur. No energy will be transmittedv from coil 45 to coil 48. 'Iube 6 is in operative condition so that the energy will be picked up-by the secondary coil 4 and be impressed upon the grids 9 and I8 of the tube 6, being amplied thereby and passed through the plate circuit thereof which includes the primary coil I5. vv Energy will be picked up by the secondary coil vI8 and impressed across primary coil I9, which is. coupled to its secondary 22 which is in turn coupled to the full wave rectier 28. The output of the rectier tube 28 is connected across resistance-25. The IR drop through the resistance 25,wi11 set up a potential across the resistance, that end of lthe resistance which is connected to thecathodebeing positive, and the other end being negative. y It will be observed that the positive end `of the resistance 25 is connected through conductor A|20 through resistance I2I, to the ground |23, through ground 98, to the cathode 96 of tube 92. The negative end of resistance 25 is connected by conductor |24 to grid |25 of tube 92, so that thev rectified current flowing through resistanced25will'cause grid |25 of tube 92 to become The 5,'

The cath- Since coil 45 is coupled :i

highly negatvewith respect to cathode 96, thus blocking the tube 92.V

It will also b e observed thatnormally a positive potential 4from battery `36. is impressed through resistance |26, conductor |20, conductor 26, resistance25, conductor |24, upon the grid of the tube92r, thus insuring a high plate current through tube 92. The IR drop across resistance 25 is suiiiciently high so that this positive potential is overcome and the grid |25 is made sufficiently highly negative to block out tube 92. As soon as the flow of plate current through resistance 99 ceases, the negative bias impressed upon the grid 3| from the resistance 99 is eliminated, and tube 32 is made operative. At the same time the plate potential on tube 56 is eliminated and that tube is made inoperative. It will be seen, therefore, that a portion of the output of secondary coil I8 is rectified in tube 28 and used to block control tube 92, which in turn unblocks output amplification tube 32 and renders input amplifier tube 56 inoperative.

The energy coming from the west then is amplied by tube 32, the amplied energy flowing through the primary coil 31, which is in the plate circuit of the tube 32, The energy is picked up by the secondary coil 42, across which the conductors 43 and 44 of the line are connected.

Howling or oscillatory action is prevented since tube 56 is automatically rendered inoperative whenever tube 32 is rendered operative. It will be seen therefore that whenever energy is being transmitted from west to east, no energy can be transmitted from east to west, since both tubes of the east to west amplifier are in inoperative condition during the passage of a signal from west to east.

The potential across resistance 25 is impressed upon a condenser |30, so that if energy being transmitted from west to east momentarily ceases, the control tube 92 will remain momentarily blocked due to the potential impressed upon the grid thereof from the condenser |30, which has become charged. It will also be observed that one side of condenser |30 is grounded at 98, so that condenser |30 is shunted by resistance 25 and resistance |2|. The charge of condenser |30 therefore is adapted to leak off through resistances |2| and 25. Any suitable time interval may be obtained by the value of condenser |30 or by altering the resistance |2|. The value of resistance 25 is determined by the IR drop necessary to block tube 92 against the potential of battery 36.

Should a signal be received from the east for transmission to the west,`the operation is the same except control tube |02 is biased out by rectied energy from rectifier tube 10 as will be apparent to those skilled in the art.

It will be observed that we have accomplished the objects of our invention. We have provided a voice operated repeater in which neither the hybrid coil nor balancing networks are employed. The received signal is amplified directly to the line and any desired gain may be had. Positive directional operation is obtained and freedom from high frequency circulatory currents or internal oscillation is achieved.

It will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and sub-combinations. This is contemplated by and is within the scope of our claims. It is further obvious that various changes may be made in details within the scope of our claims without is not to be limited to the specific details shown' and described. l

Having thus described our invention, what we claim is:

l. In a transmission system having an input thermionic tube having a grid and an output thermionic tube having a grid, said input thermionic tube normally being operative and said output tube normally being inoperative, a control thermionic tube having a plate circuit the potential of which is impressed upon the grid of the output thermionic tube to render it inoperative, a rectier tube, means for rectifying a portion of the output energy of said first thermionic tube, means for impressing said rectified energy upon the grid of said control tube to render it inoperative whereby incoming energy is adapted to render said output tube operative in response thereto.

2. In a repeating system having two one-way transmission channels each comprising an input thermionic tube and an outputthermionic tube, a pairof control tubes each adaped to render the input tube of one channel operative and the output tube of the other channel inoperative, and means operated by energy from one of said transmission channels for nullifying the action of the control tube affecting the output tube of said energy receiving channel.

3. In a two-way voice operated repeater system, a pair of one-way transmission channels each having an input tube and an output tube, control tubes for rendering the input tubes of respective channels operative, and for controlling the output power level of respective opposite output tubes, and means responsive to the output of the input tube of one of said channels for controlling the control tube governing the output tube of said channel.

4. In a repeating system having two line sections, a two-way repeating means adapted to repeat signals between line sections comprising two one-way transmission channels, each having an input thermionic tube having a grid and an output thermionic tube having a grid, a pair of control thermionic tubes cach having a plate circuit the potential of which is impressed upon the grid of respective output thermionic tubes to render them inoperative, a pair of rectifying tubes, means for rectifying a portion of the output energy of each of said input tubes, means for impressing said rectied energy upon respective grids of control tubes to render them inoperative, the construction being such that incoming energy from one direction is adapted to render the output tube of one of said transmission channels operative and the input tube of the other of said transmission channels inoperative.

5. In a repeating system having two line sections, a two-way repeating means adapted to repeat signals between line sections comprising two one-way transmission channels each having an input thermionic tube having a grid, and an output thermionic tube having a grid, a pair of control thermionic tubes each having a plate circuit, a resistance in said plate circuit, means for connecting said resistance to the plate-cathode circuit of one of said input thermionic tubes to enable the IR drop across said resistance to furnish the plate voltage for said tube, means for connecting said resistance to the grid of the output tube of the opposite transmission channel to apply a blocking voltage to the grid of said tube departing from the spirit of our invention `It is therefore, to be understood that our invention4 whereby renderingfit inoperati'v'ey 4the other of-'said control tubes being similarly providedV with a` plate circuit'having a resistance and means for similarly connecting said resistance -toenable the IR drop thereacross to act as the'plate potential for the other of said input; tubes and the grid` blocking potential of the other of said` output agrarias 

